General
"Hey mom, what's for dinner?"
"I don't know, but I've started the onions."
Onion size is dependant on the size of the tops. The bigger the green tops, the bigger the bulbs. A high nitrogen fertilizer, loose soil, and a lot of water are critical. Most of the onion bulbs should form on the surface of the soil, so don't transplant too deeply.
Latin
Allium cepa.
Alliaceae family.
Difficulty
Moderately difficult.
Planting Seeds
Sweet Mild: For big bulbs, raise transplants from Feb-mid March. Transplant into the garden in mid-April. Harvest when tops start to fall down mid-August to mid-September.
Storage: Start inside in March, or direct-seed in April. Harvest when tops start to fall down mid-August to mid-September.
Overwinter: Direct-seed in mid-August, or raise transplants to set outside in September. Starting on a seedbed at the beginning of August, these small plants will be moved to rows in the spring. Harvest when the tops start to fall down the next June.
Scallions: Direct-seed from April to August, or sow 3 seeds in each cell of a 72 cell tray, and transplant as a clump. Space clumps 15cm (6") apart.
Seeds will emerge in 6-12 days, depending on soil temperature. Optimum soil temperature 16-25 C (50-75 F). In optimal conditions, at least 75% of the seeds will germinate. Usual seed life: 1 year.
Garden: if direct-seeding: rows 30cm (1') apart, 2 seeds/cm (1/2"), 0.5cm (1/4") deep. Thin to 5-10cm (2-4") apart. Farm: 100' row of storage onions: 28g, of scallions 120g. Acre: storage onions: 1.5kg, scallions: 6-7kg.
Preparing Soil
Fertile and well-drained soil is best for onions. Add well-rotted manure or compost and band 1/2-1 cup complete organic fertilizer below each 3m (10') of row. Keep high moisture level in the top 20-30cm (8-12") of soil.
Planting
Transplanting is preferred for home gardeners: Sow 3 seeds in each cell of a 72-cell tray and transplant as a clump, spacing clumps 15cm (6") apart. Seeds will emerge in 6-12 days depending on soil temperature. Set transplants out in April. Most of the bulb should form on the surface of the soil, so don't transplant too deeply. Bulb size is dependent on the size of the tops: the bigger the tops, the bigger the bulb.
Diseases & Pests
Botrytis blast and downy mildew are common leaf diseases. One starts with white spots and streaks, the other with purple-grey areas on leaves. Leaves wither from the top down and plants die prematurely. Separate the overwintered and spring crops because disease starts in older plants and moves to younger. Avoid overhead watering and plant in open sunny locations. Use lots of compost and practice strict sanitation and rotation procedures. Spraying with copper hydroxide every 7-14 days at the first sign of a problem may help prevent disease from spreading.
The pungent odour of onions repels many pests and also protects nearby garden vegetables.
Harvest
Stop watering in the beginning of August to mature the bulbs in dry soil. After half the tops have fallen, push over the remainder, wait a week and lift the bulbs. Curing is essential for long storage. Spread bulbs out in the sun for about a week, covering them at night to protect from dew. When the outer layer of the onion changes from moist to dry and crisp, it is cured. If weather is poor, cure inside. Storage: Keep onions in mesh sacks so they get good ventilation, and hang sacks where air is dry and very cool, but not freezing. Check them regularly and remove any sprouting or rotting onions. Well-cured storage onions should keep until late spring.
Companion Plants
Beets, Broccoli, Brussels Sprouts, Cabbage family, Carrot, Cauliflower, Celery, Chamomile, Collard, Cucumber, Dill, Kale, Lettuce, Pepper, Potato, Radish, Rose, Savory, Squash, Strawberry, Tomato.
